Summary: Learn to authenticate users in Microsoft SharePoint Foundation 2010 in this four-part series. Learn to determine the identity of the caller of a Windows Communication Foundation (WCF) web service that you consume as an external content type from Microsoft Business Connectivity Services (BCS).

Windows Identity Foundation (WIF) gives you much more control over your identity logic. You can use WIF to determine the identity of the caller from inside a web service. The example that is presented in this article enhances the example that is presented in the previous article in the series, WCF: Building WCF Web Services for SharePoint 2010 Business Connectivity Services (Part 1 of 4), to determine caller identity. With each call to the web service, it appends the identity of the user calling the web service to a log file. You can then examine the log file to see caller identity.